//定义懒加载插件
import { useIntersectionObserver } from '@vueuse/core'

export const lazyPlugin = {
  install(app) {
    //懒加载指令逻辑
    app.directive('img-lazy', {
      mounted(el, binding) {
        //el：指令绑定的元素
        //binding： binding.value 指令等于号后面绑定的表达式的值
        // console.log(el,binding)
        const { stop } = useIntersectionObserver(
          el,
          ([{ isIntersecting }]) => {
            // console.log(isIntersecting)
            if (isIntersecting) {
              //进入了视口区
              el.src = binding.value
              stop()
            }
          }
        )
      }
    })
  }
}
